A deck that was a suntrap in June becomes a green skating rink by November. Timber decking in Greater Manchester soaks up damp all winter, growing a slick layer of algae that makes every step an adventure — and composite decking, for all its marketing, goes just as slippery when the green film builds up.
We clean timber and composite decking across Greater Manchester, from Manchester and Salford to Stockport, Bury, Rochdale and Wigan. The key word is care: decking is cleaned at low pressure, with the grain, with plant-safe treatments — because a deck ruined by an over-eager pressure washer is worse than a dirty one.
What is decking cleaning?
Decking cleaning is a low-pressure wash of your timber or composite deck, combined with an algae treatment that kills the slippery green growth rather than just pushing it around. The goal is a deck that is clean, safe underfoot and undamaged — which means restraint, not force.
Timber and composite need different handling. Softwood boards can furrow and splinter if the pressure is too high or the lance is held too close; composite boards can be scorched or marked by heat and harsh chemicals. We clean with a wide fan at low pressure, working along the boards, and let the treatment dwell so the chemistry does the work.
How we do it
- Check the boards and fixings: We walk the deck first, looking for split boards, raised screws and nails, soft or rotten timbers and wobbly rails. Anything that could catch the lance or trip someone gets flagged — and raised fixings are noted so they can be knocked back down before we wash.
- Clear and protect the garden: Furniture, pots and barbecues come off the deck, and the beds and lawn around it are covered or soaked so treatment run-off does not damage your plants. We check where the water will drain, especially on raised decks over soil or patios.
- Treat the algae and let it dwell: An algae treatment goes down over the whole deck, with extra attention to the shaded, north-facing boards where growth is thickest. It is left to dwell for 15 to 25 minutes — this is what kills the growth at the root, so the wash is lifting dead algae rather than fighting live slime.
- Low-pressure wash with the grain: The deck is washed with a wide fan lance at low pressure, working along the length of the boards and never across them. Gaps between boards are flushed out, where trapped leaves and soil feed the next round of algae. On composite we stay well within safe pressures to avoid marking the surface.
- Rinse and drying advice: Everything is rinsed clean, furniture goes back once the boards are dry, and we tell you how long to leave it — typically 24 to 48 hours — before any oiling or staining, so treatments go onto dry timber and actually take. We will also point out any boards that are past cleaning and need replacing.
Why have it done
- Removes the slippery algae film that makes decks dangerous in winter
- Cleans between the boards where rot and regrowth start
- Safe for softwood timber, hardwood and composite boards
- Low-pressure method protects the wood from furring and splintering
- Leaves the deck ready for oiling or staining once fully dry
Timber versus composite: different decks, different care
Softwood timber is the most vulnerable: too much pressure tears the surface fibres, leaving it furry, rough and quicker to rot. We keep the pressure low and the lance moving, which cleans without chewing the grain. Hardwood is tougher but still gets the same careful treatment.
Composite decking is often sold as maintenance-free, but it still grows algae and still needs cleaning — it just needs it gently. High pressure or hot water can mark or warp composite boards, so we use a cool, low-pressure wash with a composite-safe treatment. If your composite deck has gone patchy or streaked, it is almost always algae film, and it comes off.
Keeping your deck slip-free through winter
The algae will come back — Manchester damp sees to that — but you can slow it down. Sweep leaves off regularly so they do not sit rotting between the boards, keep pots on feet so water drains away, and trim back anything overhanging that keeps the deck in permanent shade.
A yearly clean in autumn, before the worst of the wet weather, keeps the deck safe underfoot through winter. And if the patio below the deck is going green too, our patio cleaning can be done on the same visit while the equipment is already set up.
What does it cost?
As a rough guide, decking cleaning across Greater Manchester typically falls between £60 and £150 depending on the size of the deck, whether it is timber or composite, and how much algae has built up — every job is quoted free after a look at photos or a quick site visit.
Decking Cleaning FAQs
How much does decking cleaning cost in Manchester?
Most domestic decks across Greater Manchester fall between £60 and £150. Size is the main factor, then the material — composite needs a slower, more careful clean — and the condition, since a deck that has not been touched in years takes longer than one cleaned last autumn. Photos or a quick visit get you an exact, free quote.
Will jet washing damage my wooden decking?
It will if the pressure is too high, which is why we clean decking at low pressure with a wide fan, working along the boards. That lifts the algae and grime without tearing the timber fibres — the furring and splintering people worry about comes from a narrow jet held too close, usually DIY. Your deck should come out cleaner and smoother, not rougher.
Can you clean composite decking safely?
Yes. Composite needs a cool, low-pressure wash and a composite-safe algae treatment — no harsh chemicals and no heat, which can mark or warp the boards. The patchy, streaked look most composite decks develop is just algae film, and it lifts off cleanly with the right approach. We treat composite as its own material, not as tougher timber.
How long after cleaning before I can oil or stain the deck?
Give it 24 to 48 hours of dry weather so the timber dries right through. Oil or stain applied to damp boards will not take properly and can trap moisture underneath, which does more harm than good. If the forecast is wet, wait for a dry spell — the clean keeps, and the treatment will last far longer on properly dry wood.
My deck is green again months after cleaning — is that normal?
In Greater Manchester, honestly, yes — shaded, damp decks regrow algae faster than most people expect. A yearly clean keeps it under control, and sweeping leaves off and keeping the boards clear of standing water slows it down. What the clean buys you is a safe, grippy surface through the worst months; it is maintenance, not a one-time cure.
How do I clean wooden decking without a pressure washer?
Sweep it thoroughly, then scrub along the boards with a stiff decking brush and warm water mixed with a decking cleaner or oxygen bleach, leaving it to sit for 15 to 20 minutes before scrubbing. Flush the gaps between the boards, where trapped leaves feed the algae. This handles light grime and some green growth, but it will not shift a thick winter algae film — that needs a professional treatment and wash. Think of it as maintenance between yearly cleans.
How long does decking cleaning take?
A typical domestic deck takes one to two hours, including the algae treatment dwell time, the wash and the tidy-up. Large wraparound decks or ones that have not been touched in years take longer, since the treatment needs extra time on thick growth. Composite decks are a little slower because the lower-pressure method is more deliberate. We tell you the expected time when we quote, and you can walk on the boards again once they are dry underfoot.
When is the best time of year to clean decking?
Autumn, before the worst of the wet weather. Cleaning in September or October removes the summer's grime and the early algae, leaving the boards safe and grippy through the slippery winter months when most deck accidents happen. Spring is the second-best option, clearing the winter film before you start using the garden again. Avoid cleaning just before a long wet spell if you plan to oil or stain — the timber needs 24 to 48 dry hours for that.
Can you clean a deck with rotten or damaged boards?
We can clean the sound boards, but we will not wash over timber that is genuinely rotten — soft, crumbling wood will not survive even a low-pressure wash and should be replaced first. During the survey we check every board, and we will show you anything that is past cleaning so you can get it swapped out. Cleaning first actually helps: once the algae and grime are off, the true condition of the timber is easy to see.
Will cleaning bring back the grey, weathered colour of my decking?
Cleaning removes the algae, dirt and grime, but the silvery-grey weathering is sun-bleached surface timber, not dirt — washing alone will not return the original colour. What cleaning does is prepare the deck properly for oiling or staining, which is what brings the colour back. If you want the deck to look like new, plan on a clean followed by an oil or stain once the timber is fully dry.
Does the wash get between the boards?
Yes. The gaps between the boards are one of the most important parts of the clean — trapped leaves, soil and moss sit in there holding moisture against the timber, which is where rot and the next round of algae start. We flush the gaps out as part of the wash, working along the boards so debris is pushed clear rather than driven in deeper. Keeping those gaps clear afterwards, with a regular sweep, is the single best thing you can do for your deck.
Decking Cleaning across Greater Manchester
We're mobile and cover the whole region. Pick your area: